March 28th ~ This Day in History video by History.com ~ 1979: Nuclear accident at Three Mile Island: The worst accident in the history of the U.S. nuclear power industry began when a pressure valve in the Unit-2 reactor at Three Mile Island failed to close on the 28th March 1979. Cooling water, contaminated with radiation, drained from the open valve into adjoining buildings, and the core began to dangerously overheat. The Three Mile Island nuclear power plant was built in 1974 on a sandbar onPennsylvania’s Susquehanna River, 10 miles downstream from the state capitol in Harrisburg. | & more about history on this day in the video…